This invention relates to flame resistant thermoplastic blends. More particularly, this invention relates to a certain type of salt additives which reduces the drippage of thermoplastic blends containing an aromatic brominated polycarbonate, polyester carbonate, and silicone polyimide.
Aromatic brominated polycarbonate/polyester carbonate/silicone polyimide blends are known in the art. Reference is made, for example, to U.S. Pat. No. 4,923,933 to Curry. In the Curry patent, such blends are disclosed to be flame resistant and particularly useful for the construction of aircraft interior panels and parts which must exhibit low flammability and low smoke generation characteristics. Various requirements have been placed on the flame resistance and smoke generation of materials used in the construction of panels and parts for the interiors of commercial aircraft. Exemplary flammability requirements include those set forth in the 1986 and 1990 amendments to Part 25--Airworthiness Standards--Transport Category Airplanes of Title 14, Code of Federal Regulations (See 51 Federal Register 26206, Jul. 21, 1986 and 51 Federal Register 28322, Aug. 7, 1986). The flammability standards are based on heat calorimetry tests developed at Ohio State University and are described in the above-cited amendments to 14 C.F.R. Part 25, which are hereby incorporated by reference herein.
Although such blends have good flame resistance, it is desirable to reduce the drippage which occurs when such blends are burned.